- Aqueous-phase hydrogenation of biomass-derived itaconic acid to methyl-γ-butyrolactone over Pd/C catalysts: Effect of pretreatments of active carbon
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The effect of active carbon pretreatment on the catalytic performance of Pd/C catalysts in the hydrogenation of itaconic acid was studied. The catalysts were prepared by deposition-precipitation and characterized by XRD, BET, NH3-TPD, TEM and F
- Li, Sha,Wang, Xicheng,Liu, Xiaoran,Xu, Guoqiang,Han, Sheng,Mu, Xindong
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- A series of crystal structures of a meta-cleavage product hydrolase from Pseudomonas fluorescens IP01 (CumD) complexed with various cleavage products
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Meta-cleavage product hydrolase (MCP-hydrolase) is one of the key enzymes in the microbial degradation of aromatic compounds. MCP-hydrolase produces 2-hydroxypenta-2,4-dienoate and various organic acids, according to the C6 substituent of the substrate. Comprehensive analysis of the substrate specificity of the MCP-hydrolase from Pseudomonas fluorescens IP01 (CumD) was carried out by determining the kinetic parameters for nine substrates and crystal structures complexed with eight cleavage products. CumD preferred substrates with long non-branched C6 substituents, but did not effectively hydrolyze a substrate with a phenyl group. Superimposition of the complex structures indicated that benzoate was bound in a significantly different direction than other aliphatic cleavage products. The directions of the bound organic acids appeared to be related with the kcat values of the corresponding substrates. The Ile139 and Trp143 residues on helix α4 appeared to cause steric hindrance with the aromatic ring of the substrate, which hampers base-catalyzed attack by water.
- Fushinobu, Shinya,Jun, So-Young,Hidaka, Masafumi,Nojiri, Hideaki,Yamane, Hisakazu,Shoun, Hirofumi,Omori, Toshio,Wakagi, Takayoshi
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- The Rhodium-Catalyzed Carbonylation of Linear Primary Alcohols
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The results of a comprehensive kinetic, spectroscopic, and analytical study into the rhodium-catalyzed carbonylation of primary linear alcohols (R = Me, Et, and n-Pr) are reported.In all cases, the reaction rate is first order in both and added and independent of CO pressure.The only rhodium species observed under catalytic conditions was RhI2(CO)21-.The rates of carbonylation of the alcohols decreased in the order MeOH > EtOH >n-Pr with relative rates at 170 deg C of 21:1:0.47.Apparent activation parameters have been determined.All the data are consistent with the rate-determining step being nucleophilic attack by the rhodium ion on the corresponding alkyl iodide, in agreement with the previous interpretation of the methanol system.Important information was also obatained regarding the stability of the intermediate rhodium alkyl species.Carbonylation of n-PrOH gave a mixture of the two isomeric product butyric acids, the composition of which depended on the CO pressure.The isobutyric acid appears to arise from the isomerization of the initially formed n-alkyl species, and the pressure dependence of this process suggests that loss of CO from the alkyldicarbonylrhodium(III) species is competitive with the migratory insertion reaction which forms the analogous monocarbonyl acyl species observed previously.
- Deklewa, Thomas W.,Forster, Denis
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- Aerobic oxidation of alcohols to carbonyl compounds catalyzed by N-hydroxyphthalimide (NHPI) combined with Co(acac)3
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Aerobic oxidation of various alcohols has been accomplished by using a new catalytic system. N-hydroxyphthalimide (NHPI) combined with Co(acac)3. The oxidation of alcohols by NHPI was found to be markedly enhanced by adding a slight amount of Co(acac)3 (0.05 equiv. to NHPI). Thus, secondary alcohols and vic-diols which are difficult to be oxidized by NHPI alone were smoothly oxidized with molecular oxygen (1 atm) to the corresponding carbonyl compounds under relatively mild conditions (65 ~ 75 °C).
- Iwahama, Takahiro,Sakaguchi, Satoshi,Nishiyama, Yutaka,Ishii, Yasutaka
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- An unexplored O2-involved pathway for the decarboxylation of saturated carboxylic acids by TiO2 photocatalysis: An isotopic probe study
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The aerobic decarboxylation of saturated carboxylic acids (from C 2 to C5) in water by TiO2 photocatalysis was systematically investigated in this work. It was found that the split of C 1-C2 bond of the acids to release CO2 proceeds sequentially (that is, a C5 acid sequentially forms C4 products, then C3 and so forth). As a model reaction, the decarboxylation of propionic acid to produce acetic acid was tracked by using isotopic-labeled H218O. As much as ≈42% of oxygen atoms of the produced acetic acids were from dioxygen (16O2). Through diffuse reflectance FTIR measurements (DRIFTS), we confirmed that an intermediate pyruvic acid was generated prior to the cut-off of the initial carboxyl group; this intermediate was evidenced by the appearance of an absorption peak at 1772 cm-1 (attributed to C=O stretch of α-keto group of pyruvic acid) and the shift of this peak to 1726 cm -1 when H216O was replaced by H 218O. Consequently, pyruvic acid was chosen as another model molecule to observe how its decarboxylation occurs in H2 16O under an atmosphere of 18O2. With the α-keto oxygen of pyruvic acid preserved in the carboxyl group of acetic acid, ≈24% new oxygen atoms of the produced acetic acid were from molecular oxygen at near 100% conversion of pyruvic acid. The other ≈76% oxygen atoms were provided by H2O through hole/OH radical oxidation. In the presence of conduction band electrons, O2 can independently accomplish such C1-C2 bond cleavage of pyruvic acid to generate acetic acid with ≈100% selectivity, as confirmed by an electrochemical experiment carried out in the dark. More importantly, the ratio of O2 participation in decarboxylation increased along with the increase of pyruvic acid conversion, indicating the differences between non-substituted acids and α-keto acids. This also suggests that the O 2-dependent decarboxylation competes with hole/OH-radical-promoted decarboxylation and depends on TiO2 surface defects at which Ti 4c sites are available for the simultaneous coordination of substrates and O2. Acid aerobics! An O2-involved pathway for the decarboxylation of saturated carboxylic acids by TiO2 photocatalysis is clarified, and has been found to be composed of two major tandem steps. An oxygen atom of O2 is incorporated into the product acid in the second step (see scheme).
- Wen, Bo,Li, Yue,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
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- An Efficient Synthesis of Optically Active 4-Methyloxetan-2-one: Asymmetric Hydrogenation of Diketene catalysed by binap-Ruthenium(II) Complexes
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Highly enantioselective hydrogenation of diketene with the catalytic system derived from (benzene)>Cl and triethylamine or with Ru2Cl42(NEt3) in tetrahydrofuran gives optically active 4-methyloxetan-2-one in up to 97percent selectivity and 92percent enantiomeric excess (e.e.).
- Ohta, Tetsuo,Miyake, Tsutomu,Takaya, Hidemasa
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- Lid hinge region of Penicillium expansum lipase affects enzyme activity and interfacial activation
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Saturation mutagenesis at sites displaying the highest B factors in the lid and the hinge regions of Penicillium expansum lipase (PEL) has been employed to improve the efficiency of the lipase in biocatalysis. Replacements of amino acid on beneficial mutants were identified as T66L/D70N, T66V/D70N, E83K, E83H and E83N. In substrate specificity assays, T66L/D70N was significantly more active than wild-type PEL on substrates with medium and long chain lengths. In addition this mutant also displayed a 136.4-fold increase in activity on p-nitrophenyl palmitate. Remarkably, E83K lacked interfacial activation while it was observed in wild-type PEL and the other mutants. Insight into the relation between the mutations and enzymatic properties was gained by modeling and docking studies. All these mutants showed an enhanced catalytic activity, indicating their potential in further application. Therefore, these results indicate the amino acid composition of the lid hinge region plays an extremely important role in the interfacial activation, activity and substrate specificity of PEL. Moreover, the results in this work provide a new clue for selecting critical amino acid residues for the enzyme design.
- Tang, Lianghua,Su, Min,Yan, Junzhe,Xie, Sheng,Zhang, Wenhuang
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- Effects of diluents on the reaction hazards of tributyl phosphate with nitric acid
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A proportion of 30 wt % of tributyl phosphate (TBP) in suitable diluents is the workhorse in the extraction of U and Pu in the plutonium uranium extraction (PUREX) process. Accelerating rate calorimetric (ARC) studies of effects of diluents on TBP behavior reveal a similar thermal behavior irrespective of the nature of diluents. The reactive thermal hazards of 30 wt % of TBP with 4N HNO3 in different diluents show onset temperatures in the range of 105-130 °C with a significant pressure rise. Although the onset points are closer to the operating temperature range of the PUREX process, the heat rates are small. However, the process poses pressurization hazards due to the breakdown of the structure of TBP. Oxidation of butanol to butanoic acid is the main cause for exothermic behavior in all cases.
- Sreekantan, Smitha Velayuthan,Mahadevan, Surianarayanan,Jala, Samuel Vara Kumar,Seshadri, Hariharan,Mandal, Asit Baran
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- HYDROCARBONYLATION DE LACTONES EN PRESENCE DE CATALYSEURS A BASE DE COBALT ET DE RHODIUM
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The hydrocarbonylation of lactones catalysed by rhodium and cobalt complexes is discussed.Rhodium catalysts promote the formation of mono- and di-acids, but with cobalt catalysts homologation takes place yielding lactones and acids.The addition of iodine promotors is essential.
- Bitsi, Gustave,Kheradmand, Houchang,Jenner, Gerard
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- Adsorption and degradation of Congo red on a jarosite-type compound
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Natrojarosite particles were prepared by forced hydrolysis. X-ray diffraction and field-emission scanning electron microscopy were used to characterize the resulting products. Degradation of the azo dye Congo red (CR) by natrojarosite was investigated under various conditions, such as in the presence or absence of visible-light irradiation, catalyst loading, H2O2 concentration, and initial pH. Total organic carbon determination, UV-visible spectroscopy, and direct infusion-electrospray ionization mass spectrometry in the negative ion mode provided insight into the nature of the degradation products. Moreover, a complete degradation mechanism of CR on natrojarosite was presented. The degradation of CR in the current system occurred even at neutral pH, and the total degradation rate was close to 99.1% for a 30 mg L-1 CR solution. Approximately 80% of the samples were completely mineralized and the other 20% were degraded to small-molecule products. The novel natrojarosite catalysts are potentially valuable for industrial applications because of their high activity, low iron leaching, and low cost.
- Dong, Yu,Wang, Ziting,Yang, Xin,Zhu, Meiying,Chen, Rufen,Lu, Bin,Liu, Hui
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p. 102972 - 102978
(2016)
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- Tuning the catalytic selectivity in biomass-derived succinic acid hydrogenation on FeOx-modified Pd catalysts
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Succinic acid is an important biomass-derived C4 building block and is ready to be converted into various value-added chemicals. Here we report that tunable selectivity for the formation of 1,4-butanediol, γ-butyrolactone and tetrahydrofuran from aqueous succinic acid hydrogenation could be achieved on FeOx-promoted Pd/C catalysts. Fe was found to be an efficient promoter for the succinic acid hydrogenation, which not only improved the activity of the catalysts but also tuned the product distribution. Succinic acid could be transformed into 1,4-butanediol with a yield of over 70% in the presence of the Pd-5FeOx/C catalyst under the relatively mild conditions of 200°C and 5 MPa H2. The reaction pathway was also proposed according to the reaction and characterization results.
- Liu, Xiaoran,Wang, Xicheng,Xu, Guoqiang,Liu, Qiang,Mu, Xindong,Liu, Haichao
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- Study of monometallic Pd/TiO2 catalysts for the hydrogenation of succinic acid in aqueous phase
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A series of 2 wt % Pd/TiO2 monometallic catalysts were prepared by varying some parameters, such as the nature of the precursor salt, the titania support, and the preparation method. The structural and textural properties of the catalytic systems were fully characterized by several physical and chemical techniques (inductively coupled plasma optical emission spectrometry, N2 physisorption, H2 chemisorption, transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, powder X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and gas phase reaction of cyclohexane dehydrogenation). The catalytic performances were further estimated for the hydrogenation of an aqueous solution of succinic acid (SUC) performed in a batch reactor at 160 C and under 150 bar total pressure. The results showed that all the Pd catalysts are very selective to produce γ-butyrolactone, the first hydrogenated product. However, the rate of succinic acid conversion is a function of both the Pd dispersion and the preparation method. The deposition-precipitation method allows one to obtain the highest performing 2 wt % Pd/TiO2 samples during SUC hydrogenation in terms of activity and stability.
- Tapin, Benoit,Epron, Florence,Especel, Catherine,Ly, Bao Khanh,Pinel, Catherine,Besson, Michele
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- Hetero-aromatic Nitrogen Base Promoted Cr(VI) Oxidation of Butanal in Aqueous Micellar Medium at Room Temperature and Atmospheric Pressure
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The kinetics of the oxidation of butanal by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, Triton X-100 (TX-100) and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of a promoter at 303 K. The pseudo-first-order rate constants (k obs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as picolinic acid (PA), 2, 2′-bipyridine (bipy) and 1,10-phenanthroline (phen). The product, butanoic acid, was characterized by 1H-NMR. Three promoters PA, bpy and phen are used in combination with SDS, TX-100 and CPC surfactants showing an increase in the rate of oxidation compared to the unpromoted pathway. The mechanism of the reaction path has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The TX-100 and PA combination is suitable for butanal oxidation.
- Malik, Susanta,Ghosh, Aniruddha,Saha, Bidyut
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- Applications of Homogeneous Water-gas-shift Reaction. I. Further Studies of the Hydroformylation of Propene with CO and H2O
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Polar ether solutions prepared in situ from Co2(CO)8 and 1,2-bis(diphenylphosphino)ethane (diphos) are active catalysts for the hydroformylation of propene with CO and H2O.Under the hydroformylation conditions employed, butyl(C4) or isobutyl alcohols, butyric(C4) acids, and dipropyl ketones were found to be formed as by-products.A pronounced formation of C4 alcohols was observed as the reaction temperature was increased; in fact, the catalyst solutions described above actively reduce butyraldehyde to butyl alcohol.The effects of the CO pressure and of the propene concentration on the formation of C4 aldehydes are also examined.It turns out that the water molecule as well as Co2(CO)8 and diphos are essential for the formation of catalytic intermediates, which are themselves responsible for the hydroformylation activity.
- Murata, Kazuhisa,Matsuda, Akio
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- Aerobic oxidation of primary aliphatic alcohols over bismuth oxide supported platinum catalysts in water
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Catalytic oxidation of non-activated aliphatic alcohols with molecular oxygen is rather challenging, especially in an aqueous medium in the absence of an additional base. Bismuth is usually used as a promoter of platinum-based catalysts. In this work, bismuth oxide was explored as a support, and Pt 0 nanoparticles supported on bismuth oxide (Pt/Bi2O 3) exhibited high activity for aerobic oxidation of n-butanol using water as a solvent in the absence of an additional base under optimized conditions. Besides n-butanol, liquid primary aliphatic alcohols with low solubility in water could also be smoothly oxidized into the corresponding carbonyl compounds with molecular oxygen. Pt/Bi2O3 reduced by H2 at about 200 °C showed the highest activity for aerobic oxidation of n-butanol. At this temperature, platinum oxide was reduced to Pt0 and bismuth oxide could be reduced partially which might change the surface property of bismuth oxide.
- Lu, Tianliang,Du, Zhongtian,Liu, Junxia,Ma, Hong,Xu, Jie
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- Aqueous-phase aerobic oxidation of alcohols by soluble Pt nanoclusters in the absence of base
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A soluble Pt nanocluster catalyst (Pt-GLY) is efficient in the absence of base for aqueous-phase aerobic oxidation of, in particular, non-activated alcohols with high recyclability. The Royal Society of Chemistry.
- Wang, Tao,Xiao, Chao-Xian,Yan, Liang,Xu, Lin,Luo, Jie,Shou, Heng,Kou, Yuan,Liu, Haichao
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- A study of the relationship between the structure and physicochemical parameters of a homologous series of oxprenolol esters at various pH values and temperatures
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A number of β-adrenergic blockers, including timolol and propranolol, are administered in eyedrops for the treatment of glaucoma, but their therapeutic value is limited by a relatively high incidence of cardiovascular and respiratory, side effects. Because of poor ocular bioavailability, many ocular drugs are applied in high concentrations, which give rise to both ocular and systemic side effects. Methods to increase ocular bioavailability include (a) the development of drug delivery devices designed to release drugs at controlled rates, (b) the use of various vehicles that retard precorneal drug loss, and (c) the conversion of drugs to biologically reversible derivatives (prodrugs) with increased cornea penetration properties, from which the active drugs are released by enzymatic hydrolysis. A homologous series of aliphatic esters of oxprenolol were synthesized and investigated as potential prodrugs for ocular use. The stability of each O- acyl derivative was investigated in aqueous solutions over the pH range 2.2- 9.0 at 37°C. The observed rate constants (k(obs)), shelf-lives (t90), lipophilicities, and Arrhenius parameters were determined for each ester. A study of the relationship between the structure and physicochemical parameters of the homologous series of oxprenolol esters at various pH values and temperatures was made.
- Jordan, C. Geraldine M.
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- Electrocatalytic Alcohol Oxidation with TEMPO and Bicyclic Nitroxyl Derivatives: Driving Force Trumps Steric Effects
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Bicyclic nitroxyl derivatives, such as 2-azaadamantane N-oxyl (AZADO) and 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO), have emerged as highly effective alternatives to TEMPO-based catalysts for selective oxidation reactions (TEMPO = 2,2,6,6-tetramethyl-1-piperidine N-oxyl). Their efficacy is widely attributed to their smaller steric profile; however, electrocatalysis studies described herein show that the catalytic activity of nitroxyls is more strongly affected by the nitroxyl/oxoammonium redox potential than by steric effects. The inexpensive, high-potential TEMPO derivative, 4-acetamido-TEMPO (ACT), exhibits higher electrocatalytic activity than AZADO and ABNO for the oxidation of primary and secondary alcohols. Mechanistic studies provide insights into the origin of these unexpected reactivity trends. The superior activity of ACT is especially noteworthy at high pH, where bicyclic nitroxyls are inhibited by formation of an oxoammonium hydroxide adduct.
- Rafiee, Mohammad,Miles, Kelsey C.,Stahl, Shannon S.
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- Facile preparation of recyclable biocatalyst-decorated magnetic nanobeads in aqueous media
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A facile process was developed to manufacture biocatalyst-conjugated magnetic nanobeads, which afford no loss of the intrinsic activity and enantioselectivity of biocatalysts. Up to 90% of their activities remained after six-time recycling in aqueous media.
- Sim, Yong Kyun,Jung, Suhyun,Lim, Jung Yun,Kim, Juhyun,Kim, Seong-Ho,Song, Bong Keun,Kim, Bum Tae,Lee, Hyuk,Park, Seongsoon
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- Synthesis of nanostructured carbon on Ni catalysts supported on mesoporous silica, preparation of carbon-containing adsorbents, and preparation and study of lipase-active biocatalysts
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This work continues a series of our studies on the synthesis of nanostructured carbon (NSC) by the pyrolysis of H2 + C3–C4 alkane mixtures on nickel and cobalt metal catalysts supported on chemically diverse inorganic materials (aluminosilicates, alumina, carbon) having different textural characteristics (mesoporous and macroporous supports) and shapes (granules, foamed materials, and honeycomb monoliths). Here, we consider Ni catalysts supported on granular mesoporous silica (SiO2). It has been elucidated how the yield of synthesized carbon depends on the Ni/SiO2 catalyst preparation method (homogeneous precipitation or impregnation) and on the composition of the impregnating solution, including the molar ratio of its components—nickel nitrate and urea. The morphology of catalytic NSC and Ni distribution in the silica granule have been investigated using a scanning electron microscope with an EDX analyzer. Carbon-containing composite supports (NSC/SiO2) have been employed as adsorbents for immobilizing microbial lipase. The enzymatic activity and stability of the resulting biocatalysts have been estimated in transesterification reactions of vegetable (sunflower and linseed) oils involving methyl or ethyl acetate, esterification, and synthesis of capric acid–isoamyl alcohol esters in nonaqueous media.
- Kovalenko,Chuenko,Perminova,Rudina
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- Origin of autocatalysis in the biphasic alkaline hydrolysis of C-4 to C-8 ethyl alkanoates
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The alkaline hydrolysis of C-4 to C-8 (butanoate to octanoate) ethyl esters shows autocatalytic kinetics when performed under two-phase conditions without any mixing solvent. Alkanoate anions and ethanol are the products of the reaction. A dynamic model is proposed that describes quantitatively this kinetic behavior. The model includes the main processes occurring in the biphasic medium and the corresponding thermodynamic calculations of the average size and stoichiometry of the molecular aggregates. Modeling indicates that salting-in and solvent effects caused by the alkanoate anions and ethanol determine the autocatalytic kinetics in the hydrolysis of C-4 ethyl ester where no aggregation occurs. In the C-5 to C-8 experiments, ester-containing micelles (ECM) are mainly formed by cooperative aggregation of alkanoate anions with ester molecules. ECM is formed only after a threshold concentration of the alkanoate anion has been reached. In a phase-transfer-like process, ECM carries ester molecules into the aqueous phase, where hydrolysis takes place yielding alkanoate anions. Additionally, in C-6 and C-7 ethyl ester hydrolysis, autocatalysis appears to be delayed, since acceleration only starts after the extent of hydrolysis has reached a certain level. A transient storage of alkanoate anions in a reservoir has been assumed to explain this delay. Collective adsorption of alkanoate anions at the oil-water interface, which occurs without any threshold concentration, could play the role of such a transient storage. The model also shows that empty micelles are without any kinetic importance, since they are formed at the end of reaction after the ester is completely depleted.
- Buhse,Lavabre,Nagarajan,Micheau
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- Reactions of calix[4]resorcinolarene anions with esters of carboxylic acids in H2O-DMF solvent
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Reactions of calix[4]resorcinolarene anions with para-nitrophenyl carboxylates in the H2O-DMF medium were studied. The kinetics of this process was measured by optical spectroscopy and potentiometric titration; the step of formation of acylated calixarene and the subsequent step of its hydrolysis were detected. Self-association of long-chain calixarenes into micelles decreases their reactivity with respect to that of the monomers.
- Mirgorodskaya,Kudryavtseva,Kazakova,Konovalov
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- Base-free aqueous-phase oxidation of non-activated alcohols with molecular oxygen on soluble Pt nanoparticles
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Seven soluble metal nanoparticle catalysts including Pt, Ru, Rh, Pd, Ir, Ag and Au were synthesized and studied for the aqueous-phase selective oxidation of non-activated alcohols under atmospheric pressure of O2. The effects of particle size were examined on the Pt catalysts with mean diameters of 1.5-4.9 nm. Pt nanoparticles efficiently catalyze the aerobic oxidation of alicyclic and aliphatic alcohols, in particular, primary aliphatic alcohols in the absence of any base. The particle sizes of the Pt catalysts strongly influence their activities, and the one of 1.5 nm exhibits much higher turnover frequencies. In comparison with the other metals examined in this work, it is concluded that Pt is the best metal of choice for the aerobic alcohol oxidation. Aliphatic primary alcohols reacts on the Pt catalysts more preferentially over their isomeric secondary alcohols with increasing their chain length or as they coexist. These steric effects, and the observed kinetic isotope effects with 1-C4H9OD and 1-C4D9OD are consistent with the general alcohol oxidation mechanism, which includes a sequence of elementary steps involving the formation of the alcoholate intermediates in quasi-equilibrated 1-C4H9OH dissociation on the Pt surfaces and the rate-determining hydrogen abstraction from the alcoholates. The inhibiting effects of hydroquinone, a typical radical scavenger, are indicative of the formation of radical intermediates in the H-abstraction step.
- Wang, Tao,Shou, Heng,Kou, Yuan,Liu, Haichao
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- Catalytic oxidation of ethers with H2O2 over zeolites
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Titanium Silicates (TS-1 and TS-2) catalyzed efficiently the selective oxidation of both linear and cyclic ethers into the corresponding acids and lactones respectively, using dil, H2O2 as the oxidant.
- Sasidharan,Suresh,Sudalai
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- Functional characterisation of a metagenome derived family VIII esterase with a deacetylation activity on β-lactam antibiotics
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Family VIII esterases represent a poorly characterised esterase family, with high sequence identity to class C β-lactamases, peptidases and penicillin binding proteins. This study reports on the metagenomic library screening and biochemical characterisation of a novel esterase (Est22) derived from an acidic Leachate environment. The enzyme is 423 amino acids in length and contained 22 aa signal peptide. The Est22 primary structure revealed the presence of N-terminus S-x-x-K sequence, which is also highly conserved in class C β-lactamases, peptidases as well as carboxylesterases belonging to family VIII. Phylogenetic analysis using the representative sequences from class C β-lactamases and family VIII esterases indicated that Est22 is a member of family VIII esterases. Substrate specificity profiling using p-nitrophenyl esters (C2-C16) indicated that Est22 preferred shorter chain p-nitrophenyl esters (C2-C5), a characteristic that is typical for true carboxylesterases. In addition of hydrolysing Nitrocefin, Est22 also hydrolysed first generation cephalosporin based derivatives. Detailed selectivity study using different cephalosporin based substrates indicated that Est22 selectively hydrolyse the ester bond of a cephalosporin derivatives leaving the amide bond of the β-lactam ring intact. The selective nature of Est22 makes this enzyme a potential candidate for the use in the synthesis and modification cephalosporin based molecules.
- Mokoena, Nobalanda,Mathiba, Kgama,Tsekoa, Tsepo,Steenkamp, Paul,Rashamuse, Konanani
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- Cp* iridium precatalysts for selective C-h oxidation with sodium periodate as the terminal oxidant
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Sodium periodate (NaIO4) is shown to be a milder and more efficient terminal oxidant for C-H oxidation with CpIr (Cp* = C 5Me5) precatalysts than ceric(IV) ammonium nitrate. Synthetically useful yields, regioselectivities, and functional group tolerance were found for methylene oxidation of substrates bearing a phenyl, ketone, ester, or sulfonate group. Oxidation of the natural products (-)-ambroxide and sclareolide proceeded selectively, and retention of configuration was seen in cis-decalin hydroxylation. At 60 C, even primary C-H bonds can be activated: whereas methane was overoxidized to CO2 in 39% yield without giving partially oxidized products, ethane was transformed into acetic acid in 25% yield based on total NaIO4. 18O labeling was demonstrated in cis-decalin hydroxylation with 18OH2 and NaIO 4. A kinetic isotope effect of 3.0 ± 0.1 was found in cyclohexane oxidation at 23 C, suggesting C-H bond cleavage as the rate-limiting step. Competition experiments between C-H and water oxidation show that C-H oxidation of sodium 4-ethylbenzene sulfonate is favored by 4 orders of magnitude. In operando time-resolved dynamic light scattering and kinetic analysis exclude the involvement of metal oxide nanoparticles and support our previously suggested homogeneous pathway.
- Zhou, Meng,Hintermair, Ulrich,Hashiguchi, Brian G.,Parent, Alexander R.,Hashmi, Sara M.,Elimelech, Menachem,Periana, Roy A.,Brudvig, Gary W.,Crabtree, Robert H.
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- Synthesis Gas Homologation of Aliphatic Carboxylic Acids
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A new preparative route to aliphatic carboxylic acids is described involving a novel homologation using synthesis gas catalysed by soluble ruthenium species coupled with iodide promotors.
- Knifton, John F.
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- Bioreduction of aldehydes and ketones using Manihot species
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Biocatalysis constitutes an important tool in organic synthesis, especially for the preparation of chiral molecules of biological interest. A series of aliphatic and aromatic aldehydes and two ketones were reduced using plant cell preparations from Manihot esculenta and Manihot dulcis roots. The reduced products were typically obtained in excellent yields (80-96%), and with excellent enantiomeric excess (94-98%), except for vanillin. Esters, a nitrile, and an amide were also examined, but were not reduced. Preliminary conversion rate studies are reported. This is the first attempt to perform the biotransformation of carbonyl compounds using Manihot species.
- Machado, Luciana L.,Souza, Joao Sammy N.,de Mattos, Marcos Carlos,Sakata, Solange K.,Cordell, Geoffrey A.,Lemos, Telma L.G.
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- Selective oxidation of n-butanol using gold-palladium supported nanoparticles under base-free conditions
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The base-free selective catalytic oxidation of n-butanol by O2 in an aqueous phase has been studied using Au-Pd bimetallic nanoparticles supported on titania. Au-Pd/TiO2 catalysts were prepared by different methods: wet impregnation, physical mixing, deposition-precipitation and sol immobilisation. The sol immobilisation technique, which used polyvinyl alcohol (PVA) as the stabilizing agent, gave the catalyst with the smallest average particle size and the highest stable activity and selectivity towards butyric acid. Increasing the amount of PVA resulted in a decrease in the size of the nanoparticles. However, it also reduced activity by limiting the accessibility of reactants to the active sites. Heating the catalyst to reflux with water at 90°C for 1 h was the best method to enhance the surface exposure of the nanoparticles without affecting their size, as determined by TEM, X-ray photoelectron spectroscopy and CO chemisorption analysis. This catalyst was not only active and selective towards butyric acid but was also stable under the operating conditions.
- Gandarias, Inaki,Miedziak, Peter J.,Nowicka, Ewa,Douthwaite, Mark,Morgan, David J.,Hutchings, Graham J.,Taylor, Stuart H.
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- Production of isobutyric acid from methanol by: Clostridium luticellarii
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Renewable methanol can be used as a feedstock to generate value-added multicarbon components through fermentation technologies. Recently, researchers reported the production of isobutyric acid using methanol as an electron donor with open culture systems dominated by Eubacterium sp. and Clostridium sp. Here we report the ability of Clostridium luticellarii wild-type strain to produce isobutyric acid from methanol and CO2 & H2. When growing on methanol, the supplementation of acetic and butyric acid enhanced isobutyric acid final concentration, selectivity and production rate. A maximum of 5.04 ± 0.08 g L-1 isobutyric acid was produced at a rate of 0.420 ± 0.012 g L-1 d-1and selectivity of 0.70 electron per electron of total products in batch with acetic and butyric acid as electron acceptors. The pH was also found to be a major factor influencing isobutyric acid formation with maximal production at pH 6.50. Finally, in addition to its ability to produce isomers, C. luticellarii was able to perform C2-unit elongation from methanol. Overall, this study positions C. luticellarii as a promising platform for the production of isocarboxylic acids.
- Petrognani, Camille,Boon, Nico,Ganigué, Ramon
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- Hybrid composites octyl-silica-methacrylate agglomerates as enzyme supports
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The use of immobilized enzymes as catalysts may be limited by particle size which must be larger than the mesh that retains them in the reactor. Octyl-silica (OS) beads of 70 μm average size were agglomerated to obtain hybrid organic-inorganic composites with particle sizes between 100 and 200 μm. The agglomeration process has been achieved by polymerization of methacrylate from glycidyl methacrylate and ethylene dimethacrylate in the presence of silica beads and further functionalization of the composite with octyl groups. Methacrylate content of the composite (20%) is high enough to stick OS beads, and low enough to preserve the advantages of these particles as supports. The properties of the octyl silica particles for lipase immobilization have been very closely reproduced with the octyl-silica-methacrylate (OSM) composite. Enzyme loading of 210 mg lipase per gram of support has been achieved on OSM vs 230 mg/g on OS. Also catalytic activity values are close for both catalysts, OSM-lipase remaining fully active and stable after 15 cycles in acetonitrile.
- Fernández, Oscar,Díaz, Isabel,Torres, Carlos F.,Tobajas, Montserrat,Tejedor, Víctor,Blanco, Rosa M.
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- Selective oxidation of primary alcohols mediated by nitroxyl radical in aqueous solution. Kinetics and mechanism
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The kinetics of the TEMPO-mediated oxidation of methyl α-D- glucopyranoside to sodium methyl α-D-glucopyranosiduronate were studied. An intermediate was found which was identified as the hydrated aldehyde. This was oxidised in the same manner as the alcohol, with pseudo first order rate constants ratio k(obs,ald)/k(obs,alc) = 7. The reaction mechanism is discussed with emphasis on steric factors and compared to literature data. Two different reaction pathways are postulated; under basic reaction conditions via a cyclic transition state 3 and under acid reaction conditions through an acyclic transition state 4.
- De Nooy,De Nooy, Arjan E. J.,Besemer,Besemer, Arie C.,Van Bekkum,Van Bekkum, Herman
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- Biotransformation of aromatic and heterocyclic amides by amidase of whole cells of Rhodococcus sp. MTB5: Biocatalytic characterization and substrate specificity
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In this study, an amidohydrolase activity of amidase in whole cells of Rhodococcus sp. MTB5 has been used for the biotransformation of aromatic, monoheterocyclic and diheterocyclic amides to corresponding carboxylic acids. Benzoic acid, nicotinic acid and pyrazinoic acid are carboxylic acids which have wide industrial applications. The amidase of this strain is found to be inducible in nature. The biocatalytic conditions for amidase present in the whole cells of MTB5 were optimized against benzamide. The enzyme exhibited optimum activity in 50 mM potassium phosphate buffer pH 7.0. The optimum temperature and substrate concentrations for this enzyme were 50 °C and 50 mM, respectively. The enzyme was quite stable for more than 6 h at 30 °C. It showed substrate specificity against different amides, including aliphatic, aromatic and heterocyclic amides. Under optimized reaction conditions, the amidase is capable of converting 50 mM each of benzamide, nicotinamide and pyrazinamide to corresponding acids within 100, 160 and 120 min, respectively, using 5 mg dry cell mass (DCM) per mL of reaction mixture. The respective percent conversion of these amides was 95.02%, 98.00% and 98.44% achieved by whole cells. The amidase in whole cells can withstand as high as 383 mM concentration of product in a reaction mixture and above which it undergoes product feedback inhibition. The results of this study suggest that Rhodococcus sp. MTB5 amidase has the potential for large-scale production of carboxylic acids of industrial value.
- Ismailsab, Mukram,Monisha,Reddy, Pooja V.,Santoshkumar,Nayak, Anand S.,Karegoudar, Timmanagouda B.
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- Destruction of pentachlorophenol using glow discharge plasma process
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Pentachlorophenol (PCP), found in wood preservatives and pesticides, is an a cutely toxic recalcitrant organochlorine carcinogenic compound. A point- to-plane glow discharge plasma (GDP) process was used to study the destruction of 30-50 ppm (120-188 μM) sodium salt of pentachlorophenol (PCP) in an aqueous solution. PCP was converted to less than 10% of its initial concentration in 1-3 h, at room temperature and low pressure (50 Torr). Effects of varying the headspace gas chemistry, stirring rate, pH, and current upon rate of PCP conversion were investigated. Organic acids, including formate, acetate, butyrate, and oxalate, were formed as byproducts after 1-3 h of GDP treatment of PCP. The chloride recovery suggests 50-70% dechlorination. The PCP removal rate exhibited mixed order kinetics. A reaction model developed to verify mixed order kinetics compares well with the experimental data. The increase in order may be due to the production and subsequent destruction of several reaction products throughout the process. An increase n current and stirring rate increased the rate of PCP removal in the GDP reactor. However, the rate of PCP removal decreased when the initial pH of the solution is raised to 11.4. Rapid removal of PCP was observed when the headspace gas was argon, air, or oxygen. Bench scale data was used to compare the power efficiency of the GDP process with atmospheric pressure corona discharge. Results suggest that the cost of power for PCP conversion by glow discharge was less than that of atmospheric pressure corona discharge. Additionally, the operating cost for PCP destruction in aqueous solution using UV based advanced oxidation technologies was found to be comparable with power costs for PCP conversion using GDP. Pentachlorophenol (PCP), found in wood preservatives and pesticides, is an acutely toxic recalcitrant organochlorine carcinogenic compound. A point-to-plane glow discharge plasma (GDP) process was used to study the destruction of 30-50 ppm (120-188 μM) sodium salt of pentachlorophenol (PCP) in an aqueous solution. PCP was converted to less than 10% of its initial concentration in 1-3 h, at room temperature and low pressure (50 Torr). Effects of varying the headspace gas chemistry, stirring rate, pH, and current upon rate of PCP conversion were investigated. Organic acids, including formate, acetate, butyrate, and oxalate, were formed as byproducts after 1-3 h of GDP treatment of PCP. The chloride recovery suggests 50-70% dechlorination. The PCP removal rate exhibited mixed order kinetics. A reaction model developed to verify mixed order kinetics compares well with the experimental data. The increase in order may be due to the production and subsequent destruction of several reaction products throughout the process. An increase in current and stirring rate increased the rate of PCP removal in the GDP reactor. However, the rate of PCP removal decreased when the initial pH of the solution is raised to 11.4. Rapid removal of PCP was observed when the headspace gas was argon, air, or oxygen. Bench scale data was used to compare the power efficiency of the GDP process with atmospheric pressure corona discharge. Results suggest that the cost of power for PCP conversion by glow discharge was less than that of atmospheric pressure corona discharge. Additionally, the operating cost for PCP destruction in aqueous solution using UV based advanced oxidation technologies was found to be comparable with power costs for PCP conversion using GDP.
- Sharma,Josephson,Camaioni,Goheen
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- Photoactivable heterocyclic cages in a comparative release study of butyric acid as a model drug
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Aiming: at the improvement of the photorelease of butyric acid - a model carboxylic acid drug, a set of heteroaromatic compounds based on acridine, naphtho[2,1-b]pyran, 3H-benzopyran fused julolidine and thioxo-naphtho[2,1-b]pyran were evaluated as benzyl-type phototriggers, in comparison with the well-known o-nitrobenzyl group. The corresponding ester cages were irradiated in a photochemical reactor at 254, 300, 350 and 419 nm, in two solvent systems (methanol or acetonitrile in 80:20 mixtures with HEPES buffer). Photolysis studies showed that, for some of the cages, the release of the active molecule occurred with short irradiation times using 419 nm. Time-resolved fluorescence was used to elucidate their photophysical properties and determine the decay kinetics. Studies were also carried out to assess the suitability of using two-photon excitation to address these compounds, which is advantageous if their use in biological systems is to be considered.
- Piloto, Ana M.,Hungerford, Graham,Sutter, Jens U.,Soares, Ana M.S.,Costa, Susana P.G.,Gonc?alves, M. Sameiro T.
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- Combined high degree of carboxylation and electronic conduction in graphene acid sets new limits for metal free catalysis in alcohol oxidation
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Graphene oxide, the most prominent carbocatalyst for several oxidation reactions, has severe limitations due to the overstoichiometric amounts required to achieve practical conversions. Graphene acid, a well-defined graphene derivative selectively and homogeneously covered by carboxylic groups but maintaining the high electronic conductivity of pristine graphene, sets new activity limits in the selective and general oxidation of a large gamut of alcohols, even working at 5 wt% loading for at least 10 reaction cycles without any influence from metal impurities. According to experimental data and first principles calculations, the selective and dense functionalization with carboxyl groups, combined with excellent electron transfer properties, accounts for the unprecedented catalytic activity of this graphene derivative. Moreover, the controlled structure of graphene acid allows shedding light upon the critical steps of the reaction and regulating precisely its selectivity toward different oxidation products.
- Blanco, Matiás,Mosconi, Dario,Otyepka, Michal,Medve?, Miroslav,Bakandritsos, Aristides,Agnoli, Stefano,Granozzi, Gaetano
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- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
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Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
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supporting information
p. 1474 - 1480
(2022/03/08)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Biochemical and biophysical characterisation of a small purified lipase from Rhizopus oryzae ZAC3
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The characteristics of a purified lipase from Rhizopus oryzae ZAC3 (RoL-ZAC3) were investigated. RoL-ZAC3, a 15.8 kDa protein, which was optimally active at pH 8 and 55 °C had a half-life of 126 min at 60 °C. The kinetic parameters using p-nitrophenylbuty
- Ayinla, Zainab A.,Ademakinwa, Adedeji N.,Gross, Richard A.,Agboola, Femi K.
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- Time-Dependent Self-Assembly of Copper(II) Coordination Polymers and Tetranuclear Rings: Catalysts for Oxidative Functionalization of Saturated Hydrocarbons
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This study describes a time-dependent self-assembly generation of new copper(II) coordination compounds from an aqueous-medium reaction mixture composed of copper(II) nitrate, H3bes biobuffer (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), ammonium hydroxide, and benzenecarboxylic acid, namely, 4-methoxybenzoic (Hfmba) or 4-chlorobenzoic (Hfcba) acid. Two products were isolated from each reaction, namely, 1D coordination polymers [Cu3(μ3-OH)2(μ-fmba)2(fmba)2(H2O)2]n (1) or [Cu2(μ-OH)2(μ-fcba)2]n (2) and discrete tetracopper(II) rings [Cu4(μ-Hbes)3(μ-H2bes)(μ-fmba)]·2H2O (3) or [Cu4(μ-Hbes)3(μ-H2bes)(μ-fcba)]·4H2O (4), respectively. These four compounds were obtained as microcrystalline air-stable solids and characterized by standard methods, including the single-crystal X-ray diffraction. The structures of 1 and 2 feature distinct types of metal-organic chains driven by the μ3- or μ-OH- ligands along with the μ-benzenecarboxylate linkers. The structures of 3 and 4 disclose the chairlike Cu4 rings assembled from four μ-bridging and chelating aminoalcoholate ligands along with μ-benzenecarboxylate moieties playing a core-stabilizing role. Catalytic activity of 1-4 was investigated in two model reactions, namely, (a) the mild oxidation of saturated hydrocarbons with hydrogen peroxide to form alcohols and ketones and (b) the mild carboxylation of alkanes with carbon monoxide, water, and peroxodisulfate to generate carboxylic acids. Cyclohexane and propane were used as model cyclic and gaseous alkanes, while the substrate scope also included cyclopentane, cycloheptane, and cyclooctane. Different reaction parameters were investigated, including an effect of the acid cocatalyst and various selectivity parameters. The obtained total product yields (up to 34% based on C3H8 or up to 47% based on C6H12) in the carboxylation of propane and cyclohexane are remarkable taking into account an inertness of these saturated hydrocarbons and low reaction temperatures (50-60 °C). Apart from notable catalytic activity, this study showcases a novel time-dependent synthetic strategy for the self-assembly of two different Cu(II) compounds from the same reaction mixture.
- Costa, Ines F. M.,Kirillova, Marina V.,André, Vania,Fernandes, Tiago A.,Kirillov, Alexander M.
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supporting information
p. 14491 - 14503
(2021/07/19)
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- A 3D MOF based on Adamantoid Tetracopper(II) and Aminophosphine Oxide Cages: Structural Features and Magnetic and Catalytic Properties
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This work describes an unexpected generation of a new 3D metal-organic framework (MOF), [Cu4(μ-Cl)6(μ4-O)Cu(OH)2(μ-PTAO)4]n·2nCl-EtOH·2.5nH2O, from copper(II) chloride and 1,3,5-triaza-7-phosphaadamantane 7-oxide (PTAO). The obtained product is composed of diamandoid tetracopper(II) [Cu4(μ-Cl)6(μ4-O)] cages and monocopper(II) [Cu(OH)2] units that are assembled, via the diamandoid μ-PTAO linkers, into an intricate 3D net with an nbo topology. Magnetic susceptibility measurements on this MOF in the temperature range of 1.8-300 K reveal a ferromagnetic interaction (J = +20 cm-1) between the neighboring copper(II) ions. Single-point DFT calculations disclose a strong delocalization of the spin density over the tetranuclear unit. The magnitude of exchange coupling, predicted from the broken-symmetry DFT studies, is in good agreement with the experimental data. This copper(II) compound also acts as an active catalyst for the mild oxidation and carboxylation of alkanes. The present study provides a unique example of an MOF that is assembled from two different types of adamantoid Cu4 and PTAO cages, thus contributing to widening a diversity of functional metal-organic frameworks.
- ?liwa, Ewelina I.,Nesterov, Dmytro S.,Kirillova, Marina V.,K?ak, Julia,Kirillov, Alexander M.,Smoleński, Piotr
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supporting information
p. 9631 - 9644
(2021/06/30)
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- Aqueous Persistent Noncovalent Ion-Pair Cooperative Coupling in a Ruthenium Cobaltabis(dicarbollide) System as a Highly Efficient Photoredox Oxidation Catalyst
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An original cooperative photoredox catalytic system, [RuII(trpy)(bpy)(H2O)][3,3′-Co(1,2-C2B9H11)2]2 (C4; trpy = terpyridine and bpy = bipyridine), has been synthesized. In this system, the photoredox metallacarborane catalyst [3,3′-Co(1,2-C2B9H11)2]- ([1]-) and the oxidation catalyst [RuII(trpy)(bpy)(H2O)]2+ (C2′) are linked by noncovalent interactions and not through covalent bonds. The noncovalent interactions to a large degree persist even after water dissolution. This represents a step ahead in cooperativity avoiding costly covalent bonding. Recrystallization of C4 in acetonitrile leads to the substitution of water by the acetonitrile ligand and the formation of complex [RuII(trpy)(bpy)(CH3CN)][3,3′-Co(1,2-C2B9H11)2]2 (C5), structurally characterized. A significant electronic coupling between C2′ and [1]- was first sensed in electrochemical studies in water. The CoIV/III redox couple in water differed by 170 mV when [1]- had Na+ as a cation versus when the ruthenium complex was the cation. This cooperative system leads to an efficient catalyst for the photooxidation of alcohols in water, through a proton-coupled electron-transfer process. We have highlighted the capacity of C4 to perform as an excellent cooperative photoredox catalyst in the photooxidation of alcohols in water at room temperature under UV irradiation, using 0.005 mol % catalyst. A high turnover number (TON = 20000) has been observed. The hybrid system C4 displays a better catalytic performance than the separated mixtures of C2′ and Na[1], with the same concentrations and ratios of Ru/Co, proving the history relevance of the photocatalyst. Cooperative systems with this type of interaction have not been described and represent a step forward in getting cooperativity avoiding costly covalent bonding. A possible mechanism has been proposed.
- Guerrero, Isabel,Vi?as, Clara,Fontrodona, Xavier,Romero, Isabel,Teixidor, Francesc
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p. 8898 - 8907
(2021/06/28)
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- Atomically Dispersed Co Clusters Anchored on N-doped Carbon Nanotubes for Efficient Dehydrogenation of Alcohols and Subsequent Conversion to Carboxylic Acids
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The catalytic dehydrogenation of readily available alcohols to high value-added carbonyl compounds is a research hotspot with scientific significance. Most of the current research about this reaction is performed with noble metal-based homogeneous catalysts of high price and poor reusability. Herein, highly dispersed Co-cluster-decorated N-doped carbon nanotubes (Co/N-CNTs) were fabricated via a facile strategy and used for the dehydrogenation of alcohols with high efficiency. Various characterization techniques confirmed the presence of metallic Co clusters with almost atomic dispersion, and the N-doped carbon supports also enhanced the catalytic activity of Co clusters in the dehydrogenation reaction. Aldehydes as dehydrogenation products were further transformed in situ to carboxylic acids through a Cannizzaro-type pathway under alkaline conditions. The reaction pathway of the dehydrogenation of alcohols was clearly confirmed by theoretical calculations. This work should provide an effective and simple approach for the accurate design and synthesis of small Co-clusters catalysts for the efficient dehydrogenation-based transformation of alcohols to carboxylic acids under mild reaction conditions.
- Dong, Zhengping,Fang, Jian,Li, Boyang,Xu, Dan,Zhang, Fengwei,Zhao, Hong,Zhu, Hanghang
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p. 4536 - 4545
(2021/09/22)
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- Synergistic Catalytic?Effect?of N-Hydroxyphthalimide/Cobalt Tetraamide Phthalocyanine and Its Application for Aerobic Oxidation of Hydrocarbons and Alcohols
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Abstract: The activation of oxygen?for?selective?oxidation?of?organic molecules, such as hydrocarbons and alcohols, remains a major catalytic?challenge. We have developed a catalytic system combining N-hydroxyphthalimide (NHPI) with cobalt tetraamide phthalocyanine [CoPc(CONH2)4] for the oxidation of hydrocarbons and alcohols at 75?°C under an oxygen atmosphere. CoPc(CONH2)4 was synthesized by trimellitic anhydride-urea method, and its structure was confirmed by FT-IR, UV–Vis and XRD. This catalyst, in synergy with NHPI/O2 system, exhibited excellent catalytic ability and high selectivity in the oxidation of hydrocarbons and alcohols. Based on the experimental results, a reasonable reaction mechanism was proposed for the oxidation of alkanes and alcohols, respectively. Graphic Abstract: Cobalt tetraamide phthalocyanine (CoPc(CONH2)4) was synthesized by a simple solid-thermal method, and the synergistic catalysis oxidation of NHPI and CoPc(CONH2)4 was studied. A synergistic catalysis system for the aerobic oxidation of hydrocarbons and alcohols by N-hydroxyphthalimide combined with cobalt tetraamide phthalocyanine has been developed.[Figure not available: see fulltext.]
- Li, Fei,Tang, Shuo,Tang, Zhilin,Ye, Lingjun,Li, Hehua,Niu, Fanfan,Sun, Xiaoling
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- Green, homogeneous oxidation of alcohols by dimeric copper(II) complexes
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Three pyrazole derivatives, 3,5-dimethyl-1H-pyrazole (DMPz) (I), 3-methyl-5-phenyl-1H-pyrazole (MPPz) (II), and 3,5-diphenyl-1H-pyrazole (DPPz) (III), were prepared via reacting semicarbazide hydrochloride with the acetylacetone, 1-phenylbutane-1,3-dione, and 1,3-diphenylpropane-1,3-dione, respectively. Complexes 1–3 were isolated by reacting CuCl2·2H2O with I–III, respectively, and characterized by CHNS elemental analyses, FT-IR, UV-Vis, 1H and 13C NMR, EPR spectra, and TGA/DTA. Molecular structures of the pyrazole derivatives I–III and copper(II) complexes 2 and 3 were studied through single-crystal XRD analysis to confirm their molecular structures. Overlapping of hyperfine splitting in the EPR spectra of the dimeric copper(II) complexes 1–3 indicates that both copper centers do not possess the same electronic environment in solution. The copper(II) complexes are dimeric in solid state as well as in solution and catalyze the oxidation of various primary and secondary alcohols selectively. Catalysts 1–3 show more than 92% product selectivity toward ketones during the oxidation of secondary alcohols. Surprisingly primary alcohols, which are relatively difficult to oxidize, produce carboxylic acid as a major product (48%–90% selectivity) irrespective of catalytic systems. The selectivity for carboxylic acid rises with decreasing the carbon chain length of the alcohols. An eco-friendly and affordable catalytic system for oxidation of alcohols is developed by the utilization of H2O2, a green oxidant, and water, a clean and greener solvent, which is a notable aspect of the study.
- Maurya, Abhishek,Haldar, Chanchal
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p. 885 - 904
(2020/12/18)
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- One-Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho-Naphthoquinone-Catalyzed and TBHP-Promoted Oxidation Sequence
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Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
- Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
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supporting information
p. 18150 - 18155
(2021/12/09)
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- Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
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Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
- Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
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- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
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The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
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supporting information
p. 9140 - 9146
(2021/11/23)
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- Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions
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The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging. In this study, acidic poly(ionic liquid)s with swelling ability (SAPILs) were designed and synthesized via the free radical copolymerization of ionic liquid monomers, sodium p-styrenesulfonate, and crosslinkers, followed by acidification. The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength. The thermogravimetric analysis results in the temperature range of 300–345 °C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H) (245 °C). Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional (3D) honeycomb structure in water, which was ascribed to the swelling-induced self-assembly of the molecules. Moreover, we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol, and determined that their catalytic activity was much higher than that of homogeneous acid catalysts. The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures. Depending on the reaction mixture, the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it, which suggested the high enrichment ability of SAPILs for cyclohexyl acetate. The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate, which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.
- Chen, Bihua,Deng, Xi,Ding, Tong,Gao, Guohua,Ma, Sanguan,Ni, Bing,Wang, Xin,Zhang, Dawei,Zhang, Yongya
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p. 297 - 309
(2020/07/25)
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- Electrochemical oxidation of diclofenac on CNT and M/CNT modified electrodes
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The electrochemical oxidation of diclofenac (DCF), a non-steroidal anti-inflammatory drug considered as an emerging pollutant (frequently detected in wastewater), was investigated on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in aqueous media. The electroreactivity of DCF on these modified electrodes was studied using cyclic voltammetry and the kinetic parameters were calculated from the scan rate study. Cyclic voltammograms show several oxidation processes, which confirm the interaction between DCF and the catalyst surface necessary for direct oxidation processes. Constant potential electrolysis of DCF was carried out on carbon nanotubes (CNT) and metal supported CNT (M/CNT) modified electrodes, in 0.1 M NaOH and 0.1 M Na2CO3/NaHCO3buffer media. The highest DCF conversion (88% after 8 h of electrolysis) was found in carbonate buffer medium, for Ru/CNT, while the best carbon mineralization efficiency (corresponding to 48% of the oxidized DCF) was obtained on Pt/CNT modified electrode in 0.1 M NaOH medium. The products of the electrolyses were identified and quantified by HPLC-MS, GC-MS, HPLC-UV-RID and IC. The results show the presence of some low molecular weight carboxylic acids, confirming the cleavage of the aromatic rings during the oxidation process.
- Ferreira, M.,Figueiredo, J. L.,Fonseca, A. M.,Güney, S.,Ku?niarska-Biernacka, I.,Neves, I. C.,Parpot, P.,Pereira, M. F. R.,Soares, O. S. G. P.
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p. 12622 - 12633
(2021/07/25)
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- Constructing an Acidic Microenvironment by MoS2 in Heterogeneous Fenton Reaction for Pollutant Control
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Although Fenton or Fenton-like reactions have been widely used in the environment, biology, life science, and other fields, the sharp decrease in their activity under macroneutral conditions is still a large problem. This study reports a MoS2 cocatalytic heterogeneous Fenton (CoFe2O4/MoS2) system capable of sustainably degrading organic pollutants, such as phenol, in a macroneutral buffer solution. An acidic microenvironment in the slipping plane of CoFe2O4 is successfully constructed by chemically bonding with MoS2. This microenvironment is not affected by the surrounding pH, which ensures the stable circulation of Fe3+/Fe2+ on the surface of CoFe2O4/MoS2 under neutral or even alkaline conditions. Additionally, CoFe2O4/MoS2 always exposes “fresh” active sites for the decomposition of H2O2 and the generation of 1O2, effectively inhibiting the production of iron sludge and enhancing the remediation of organic pollutants, even in actual wastewater. This work not only experimentally verifies the existence of an acidic microenvironment on the surface of heterogeneous catalysts for the first time, but also eliminates the pH limitation of the Fenton reaction for pollutant remediation, thereby expanding the applicability of Fenton technology.
- Huang, Kai,Lian, Cheng,Liang, Lihong,Xing, Mingyang,Yan, Qingyun,Yin, Pengcheng,Yu, Haoran,Zhang, Jinlong
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supporting information
p. 17155 - 17163
(2021/07/06)
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- Membrane transport inspired hydrolysis of non-activated esters at near physiological pH
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A positively charged micelle loaded with substrates was transported selectively to the reaction site (cathode) to promote the proximity and localization of the reactants (ester and hydroxide). The guided vehicular delivery coupled with electrolysis allows the hydrolysis of non-activated esters at near physiological pH with significant yields along with recyclability.
- De Sarkar, Suman,Mahanty, Kingshuk,Mandal, Raki,Mandal, Subhendu,Tarafdar, Pradip K.
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supporting information
p. 11088 - 11091
(2021/10/30)
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- Mechanistic Investigation of the Nickel-Catalyzed Carbonylation of Alcohols
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The carbonylation of alcohols represents a straightforward and atom-efficient methodology for the preparation of carboxylic acids. It is desirable to perform these reactions under precious metal-free and low-pressure conditions, with regioselectivity control. In this work, we present a detailed mechanistic study of a catalytic system based on NiI2, which can carbonylate benzylic alcohols in a highly regioselective manner to the corresponding branched carboxylic acids, core motifs for nonsteroidal drugs. The combination of catalytic amounts of nickel and iodide is crucial for efficient catalytic and regioselective conversion. Quantum-chemical computations were used to evaluate the underlying mechanistic processes. They revealed that a combination of two mechanisms is responsible for the observed reactivity and that the oxidative addition of alkyl halides to the Ni(0) species follows a radical oxidation pathway via two one-electron steps.
- Comba, Peter,Ghosh, Tamal,Hashmi, A. Stephen K.,Krieg, Saskia,Menche, Maximilian,Paciello, Rocco,Rück, Katharina S. L.,Sabater, Sara,Sch?fer, Ansgar,Schaub, Thomas
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supporting information
(2020/03/19)
-
- Catalytic Oxidative Deamination by Water with H2Liberation
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Selective oxidative deamination has long been considered to be an important but challenging transformation, although it is a common critical process in the metabolism of bioactive amino compounds. Most of the synthetic methods developed so far rely on the use of stoichiometric amounts of strong and toxic oxidants. Here we present a green and efficient method for oxidative deamination, using water as the oxidant, catalyzed by a ruthenium pincer complex. This unprecedented reaction protocol liberates hydrogen gas and avoids the use of sacrificial oxidants. A wide variety of primary amines are selectively transformed to carboxylates or ketones in good to high yields. It is noteworthy that mechanistic experiments and DFT calculations indicate that in addition to serving as the oxidant, water also plays an important role in assisting the hydrogen liberation steps involved in amine dehydrogenation.
- Tang, Shan,Rauch, Michael,Montag, Michael,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 20875 - 20882
(2020/12/23)
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- Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
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Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.
- Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
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p. 3150 - 3154
(2020/06/19)
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- Oxidation of aromatic and aliphatic aldehydes to carboxylic acids by Geotrichum candidum aldehyde dehydrogenase
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Oxidation reaction is one of the most important and indispensable organic reactions, so that green and sustainable catalysts for oxidation are necessary to be developed. Herein, biocatalytic oxidation of aldehydes was investigated, resulted in the synthesis of both aromatic and aliphatic carboxylic acids using a Geotrichum candidum aldehyde dehydrogenase (GcALDH). Moreover, selective oxidation of dialdehydes to aldehydic acids by GcALDH was also successful.
- Hoshino, Tomoyasu,Yamabe, Emi,Hawari, Muhammad Arisyi,Tamura, Mayumi,Kanamaru, Shuji,Yoshida, Keisuke,Koesoema, Afifa Ayu,Matsuda, Tomoko
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- Substrate hydrophobicity and enzyme modifiers play a major role in the activity of lipase from: Thermomyces lanuginosus
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Lipase from Thermomyces lanuginosus (TL) displays high affinity for long-chain substrates, such as triolein and other long-chain triacylglycerols. Aiming to broaden the substrate chain-length specificity, different aldehydes (naphthaldehyde, butyraldehyde, hexyl aldehyde and dodecyl aldehyde) and naphthyl isothiocyanate were grafted onto lipase TL through lysine coupling. The catalytic activity of the modified lipases was investigated by reaction with substrates differing in the aliphatic chain size (p-nitrophenyl benzoate, p-nitrophenyl acetate, p-nitrophenyl butyrate, p-nitrophenyl hexanoate, p-nitrophenyl octanoate, p-nitrophenyl laurate and p-nitrophenyl palmitate). The enzymes modified with aldehydes revealed higher activity than the enzymes modified with the isothiocyanate. The most notable results were achieved for lipase TL grafted with 4 units of a dodecyl chain (TL5), which revealed the highest activity against all the tested substrates, being 10-fold more active than the native enzyme for smaller substrates (acetate and butyrate chains) and 2-fold for longer substrates (laurate and palmitate chains). The kinetic parameters evaluated (Vmax, KM and kcat/KM) also confirmed the significant catalytic performance of TL5 compared to the native enzyme. The increase in activity revealed by the modified lipases was directly proportional to the size and hydrophobicity of the linkers' aliphatic chain. Small conformational changes, either on the enzyme's lid or on the cavity of the active site were suggested by molecular dynamics simulations, circular dichroism and fluorescence spectroscopy. Moreover, the grafting with aldehydes or with the isothiocyanate conferred higher thermostability to the lipase. The chemical surface modification developed efficiently improved the activity of lipase TL, broadening the substrate's chain-length specificity, increasing thereafter the substrate possibilities for industrial reactions. This journal is
- Castro, Tarsila G.,Cavaco-Paulo, Artur,Noro, Jennifer,Silva, Carla
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p. 5913 - 5924
(2020/10/08)
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- METHOD FOR PRODUCING ALCOHOL
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PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
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Paragraph 0101-0108; 0125-0130
(2020/11/26)
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- Electrochemical oxidation of amoxicillin on carbon nanotubes and carbon nanotube supported metal modified electrodes
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The electrolysis of amoxicillin (AMX) was carried out on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in 0.1 M NaOH, 0.1 M NaCl and 0.1 M Na2CO3/NaHCO3 buffer (pH 10) media with the aim of studying the significance of two factors, electrode material and pH, on the oxidative degradation and mineralization of AMX. For this purpose, the electrolysis products were identified by HPLC-MS and GC–MS, and quantified by HPLC-UV-RID and IC. The highest carbon mineralization efficiency, corresponding to 30% of the oxidized AMX, was found for Pt/CNT modified electrode in carbonate buffer medium. Regarding to the AMX conversion, the results show that the effect of pH is higher than that of the electrode material. Principal component analysis allowed to determine the experimental parameters vs. product distribution relationship and to elucidate the oxidation pathways for the studied electrodes. The results show that the hydroxylation of the aromatic ring and the nitrogen atom play an important role on the efficient degradation of AMX.
- Ferreira, Marta,Kuzniarska-Biernacka, Iwona,Fonseca, António M.,Neves, Isabel C.,Soares, Olívia S.G.P.,Pereira, Manuel F.R.,Figueiredo, José L.,Parpot, Pier
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p. 322 - 331
(2019/07/10)
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- Sn-Catalyzed Criegee-Type Rearrangement of Peroxyoxindoles Enabled by Catalytic Dual Activation of Esters and Peroxides
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We report here the Sn-catalyzed mild protocol for ring expansion of peroxyoxindoles to afford the series of substituted-2H-benzo[b][1,4]oxazin-3(4H)-one derivatives. In this protocol, we showed the in situ conversion of tert-butyl peroxy compounds into peresters with the aid of external esters, which then underwent the ring-expansion process, and the incipient carbocation was trapped with the alcohol residue generated from the esters. The reaction is also demonstrated in a continuous flow process to afford the rearranged product in 22 min of residence time.
- Chaudhari, Moreshwar B.,Gnanaprakasam, Boopathy,Jayan, Krishna
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p. 3374 - 3382
(2020/03/23)
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- Synthesis of α,β- and β-Unsaturated Acids and Hydroxy Acids by Tandem Oxidation, Epoxidation, and Hydrolysis/Hydrogenation of Bioethanol Derivatives
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We report a reaction platform for the synthesis of three different high-value specialty chemical building blocks starting from bio-ethanol, which might have an important impact in the implementation of biorefineries. First, oxidative dehydrogenation of ethanol to acetaldehyde generates an aldehyde-containing stream active for the production of C4 aldehydes via base-catalyzed aldol-condensation. Then, the resulting C4 adduct is selectively converted into crotonic acid via catalytic aerobic oxidation (62 % yield). Using a sequential epoxidation and hydrogenation of crotonic acid leads to 29 % yield of β-hydroxy acid (3-hydroxybutanoic acid). By controlling the pH of the reaction media, it is possible to hydrolyze the oxirane moiety leading to 21 % yield of α,β-dihydroxy acid (2,3-dihydroxybutanoic acid). Crotonic acid, 3-hydroxybutanoic acid, and 2,3-dihydroxybutanoic acid are archetypal specialty chemicals used in the synthesis of polyvinyl-co-unsaturated acids resins, pharmaceutics, and bio-degradable/ -compatible polymers, respectively.
- Faria, Jimmy,Komarneni, Mallik R.,Li, Gengnan,Pham, Tu,Resasco, Daniel E.,Ruiz, Maria P.,Santhanaraj, Daniel
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supporting information
p. 7456 - 7460
(2020/03/23)
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- Metal-free Photocatalytic Aerobic Oxidative Cleavage of C?C Bonds in 1,2-Diols
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The preparation of carbonyl compounds by the aerobic oxidative cleavage of C?C bonds in 1,2-diols under mild reaction conditions is a very significant reaction and is widely employed in various scenarios. Avoiding the use of harmful stoichiometric oxidants and adopting a greener chemical process remain a challenge for this reaction to date. In this manuscript, a heterogeneous metal-free photocatalytic strategy without any additive was developed for aerobic oxidative cleavage of C?C bonds in 1,2-diols at ambient conditions with visible light. The reaction mechanism was further studied through a series of control experiments and density functional theory (DFT) calculations. In addition, the catalytic system showed a broad substrates scope, including aliphatic (linear or cyclic) 1,2-diols, benzylic, alkenyl 1,2-diols, and α-hydroxy acids (such as lactic acid). Thus, this strategy could serve as a method for the transformation of 1,2-diols to corresponding carbonyl compounds by the aerobic oxidative cleavage of C?C bonds.
- Zhu, Rui,Zhou, Gongyu,Teng, Jia-nan,Li, Xinglong,Fu, Yao
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p. 5248 - 5255
(2020/08/21)
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- PROCESS FOR MAKING CARBOXYLIC ACIDS
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An integrated process for the preparation of carboxylic acids using iso-paraffins is provided. The process includes oxidatively carbonylating a compound having a carbon-hydrogen bond with dialkyl peroxide, carbon monoxide and water. Concurrently, the iso-paraffin is converted to iso-alcohol. The process provides access to a wide range of useful carboxylic acids and operates under relatively mild conditions.
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Paragraph 0078
(2020/08/25)
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- PRODUCTION METHOD OF AMIDE COMPOUND
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PROBLEM TO BE SOLVED: To provide a production method of an amide compound, which can use a variety of carboxylic acid halides and can produce a desired amide compound at a yield higher than a batch process by suppressing a side reaction. SOLUTION: Provided is a production method of an amide compound using a flow type reactor, in which the flow type reactor includes: a first flow path; a second flow path; a first mixing means provided at a confluent part of the first flow path and the second flow path; and a third flow path that is connected to the first mixing means and arranged on a down stream side of the first mixing means, the production method comprising: a mixing step of obtaining a mixed liquid by circulating a first liquid containing the carboxylic acid halide in the first flow path, circulating a second liquid containing an amine compound having a molecular weight of 1,000 or less, an inorganic alkali and water in the second flow path, and mixing the first liquid and the second liquid by the first mixing means to obtain a mixture; and a reaction step of obtaining an amide compound by circulating the mixed liquid in the third flow path and reacting the carboxylic acid halide and the amine compound in the third flow path. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPO&INPIT
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-
Paragraph 0134-0137
(2020/10/08)
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- Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
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The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
- Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 14365 - 14373
(2019/09/06)
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- Characterization of one novel microbial esterase WDEst9 and its use to make l-methyl lactate
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Chiral lactic acids and their ester derivatives are crucial building blocks and intermediates for the synthesis of a great variety of valuable functional materials and pharmaceuticals. Before our study, the reports about the enantioselective preparation of pure L-lactic acid and its ester derivatives through direct hydrolysis of racemic substrate were quite rare. Herein, we heterologously expressed and functionally characterized one novel microbial esterase WDEst9 from Dactylosporangium aurantiacum, which exhibited high resistance to diverse metal ions, organic solvents, surfactants, NaCl and KCl. We further utilized WDEst9 as a green biocatalyst in the kinetic resolution of (±)-methyl lactate through direct hydrolysis and generated L-methyl lactate with high enantiomeric excess (e.e. >99%) and high yield (>86%) after process optimization. Notably, the enantioselectivity of WDEst9 was opposite than that of two previously reported esterases PHE14 and BSE01701 that can generate D-methyl lactate though kinetic resolution of (±)-methyl lactate. Microbial esterase WDEst9 is a promising green biocatalyst in the preparation of valuable chiral chemicals and opens the door for the identification of useful industrial enzymes and biocatalysts from the genus Dactylosporangium.
- Wang, Yilong,Xu, Shan,Li, Renqiang,Sun, Aijun,Zhang, Yun,Sai, Ke,Hu, Yunfeng
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p. 190 - 200
(2018/12/11)
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- Mild C-H functionalization of alkanes catalyzed by bioinspired copper(ii) cores
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Three new copper(ii) coordination compounds formulated as [Cu(H1.5bdea)2](hba)·2H2O (1), [Cu2(μ-Hbdea)2(aca)2]·4H2O (2), and [Cu2(μ-Hbdea)2(μ-bdca)]n (3) were generated by aqueous medium self-assembly synthesis from Cu(NO3)2, N-butyldiethanolamine (H2bdea) as a main N,O-chelating building block and different carboxylic acids [4-hydroxybenzoic (Hhba), 9-anthracenecarboxylic (Haca), or 4,4′-biphenyldicarboxylic (H2bdca) acid] as supporting carboxylate ligands. The structures of products range from discrete mono- (1) or dicopper(ii) (2) cores to a 1D coordination polymer (3), and widen a family of copper(ii) coordination compounds derived from H2bdea. The obtained compounds were applied as bioinspired homogeneous catalysts for the mild C-H functionalization of saturated hydrocarbons (cyclic and linear C5-C8 alkanes). Two model catalytic reactions were explored, namely the oxidation of hydrocarbons with H2O2 to a mixture of alcohols and ketones, and the carboxylation of alkanes with CO/S2O82- to carboxylic acids. Both processes proceed under mild conditions with a high efficiency and the effects of different parameters (e.g., reaction time and presence of acid promoter, amount of catalyst and solvent composition, substrate scope and selectivity features) were studied and discussed in detail. In particular, an interesting promoting effect of water was unveiled in the oxidation of cyclohexane that is especially remarkable in the reaction catalyzed by 3, thus allowing a potential use of diluted, in situ generated solutions of hydrogen peroxide. Moreover, the obtained values of product yields (up to 41% based on alkane substrate) are very high when dealing with the C-H functionalization of saturated hydrocarbons and the mild conditions of these catalytic reactions (50-60 °C, H2O/CH3CN medium). This study thus contributes to an important field of alkane functionalization and provides a notable example of new Cu-based catalytic systems that can be easily generated by self-assembly from simple and low-cost chemicals.
- Kirillova, Marina V.,Fernandes, Tiago A.,André, Vania,Kirillov, Alexander M.
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supporting information
p. 7706 - 7714
(2019/08/30)
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- Lipase-Powered Mesoporous Silica Nanomotors for Triglyceride Degradation
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We report lipase-based nanomotors that are capable of enhanced Brownian motion over long periods of time in triglyceride solution and of degrading triglyceride droplets that mimic “blood lipids”. We achieved about 40 min of enhanced diffusion of lipase-modified mesoporous silica nanoparticles (MSNPs) through a biocatalytic reaction between lipase and its corresponding water-soluble oil substrate (triacetin) as fuel, which resulted in an enhanced diffusion coefficient (ca. 50 % increase) at low triacetin concentration (10 mm). Lipase not only serves as the power engine but also as a highly efficient cleaner for the triglyceride droplets (e.g., tributyrin) in PBS solution, which could yield potential biomedical applications, for example, for dealing with diseases related to the accumulation of triglycerides, or for environmental remediation, for example, for the degradation of oil spills.
- Wang, Lei,Hortel?o, Ana C.,Huang, Xin,Sánchez, Samuel
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p. 7992 - 7996
(2019/05/21)
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- Ruthenium Catalyzed Dehydrogenation of Alcohols and Mechanistic Study
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We synthesized pyridylamine ligated arene-Ru(II) complexes and employed these complexes for the catalytic acceptorless dehydrogenation of primary alcohols to carboxylic acids. All the synthesized complexes [Ru]-1-[Ru]-10 are characterized using several spectro-analytical techniques, and the structures of complexes [Ru]-1, [Ru]-2, and [Ru]-5 are determined using single crystal X-ray crystallography. Efficient catalytic conversion of primary alcohols to potassium carboxylates or carboxylic acids is achieved in toluene with the quantitative release of hydrogen gas. The studied protocol for carboxylic acid synthesis with hydrogen generation is also employed for a wide range of substrates, including aliphatic alcohols, aromatic alcohols, and heteroaromatic alcohols, to obtain respective carboxylic acids in good yields (up to 86%). The studied arene-Ru catalysts also exhibit superior catalytic activity for the bulk reaction to achieve a turnover number of 1378. Moreover, extensive mass investigations are also performed to elucidate the mechanistic pathway by identifying the crucial catalytic intermediates, including aldehyde and diol coordinated Ru species under the catalytic and controlled reaction conditions.
- Awasthi, Mahendra K.,Singh, Sanjay K.
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supporting information
p. 14912 - 14923
(2019/11/03)
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- Dehydrogenation of Alcohols to Carboxylic Acid Catalyzed by in Situ-Generated Facial Ruthenium- CPP Complex
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A selective catalytic system for the dehydrogenation of primary alcohols to carboxylic acids using a facial ruthenium complex generated in situ from the [Ru(COD)Cl2]n and a hybrid N-heterocyclic carbene (NHC)-phosphine-phosphine ligand (CPP) has been first reported. The facial coordination model was unveiled by NMR analysis of the reaction mixture. Such a fac-ruthenium catalyst system exhibited high catalytic activity and stability, and a high turnover number of 20 000 could be achieved with catalyst loading as low as 0.002 mol %. The exceedingly high catalyst stability was tentatively attributed to both the anchoring role of NHC and the hemi-lability of phosphines. The catalytic system also features a wide substrate scope. In particular, the facial coordination of CPP ligands was found to be beneficial for sterically hindered alcohols, and ortho-substituted benzylic alcohols and bulky adamantanyl methanol as well as cholesterol were all found to be viable dehydrogenation substrates.
- Liu, Hui-Min,Jian, Lei,Li, Chao,Zhang, Chun-Chun,Fu, Hai-Yan,Zheng, Xue-Li,Chen, Hua,Li, Rui-Xiang
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supporting information
p. 9151 - 9160
(2019/08/12)
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- Fe3O4@SiO2@Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime
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An efficient and environmentally friendly oxidation process for the one-pot preparation of oxime, imine and carbonyl compounds through alcohol oxidation in the presence of H2O2 and/or O2 have been developed by a melamine-Mn(III) Schiff base complex supported on Fe3O4@SiO2–Cl nanoparticles, named as Fe3O4@SiO2@Im[Cl]Mn(III)-complex nanocomposite, at room temperature. Direct oxidation of alcohol to carboxylic acid was performed using the catalyst in the presence of molecular O2 at room temperature in a different approach. The oxidation products were obtained with excellent yields and high TOFs. The properties of the catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (C, H, N), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP), cyclic voltammetry (CV), nuclear magnetic resonance (1H & 13C NMR), vibration sample magnetometer (VSM), Brunauer– Emmett–Teller (BET) and differential pulse voltammetry (DPV) analyses. The mechanism of the oxidation processes was investigated for the both H2O2 and O2 oxidants. The role of the imidazolium moiety in the catalyst as a secondary functionality was investigated. Chemoselectivity behavior of the catalyst was studied by some combinations. The catalyst could be recycled from the reaction mixture by a simple external magnet and reused for several times without any considerable reactivity loss.
- Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
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p. 230 - 249
(2019/03/28)
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- Defect engineering of nickel hydroxide nanosheets by Ostwald ripening for enhanced selective electrocatalytic alcohol oxidation
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Selective electrocatalytic oxidation (ECO) of alcohols to aldehydes or acids is an environmentally friendly and economical method in modern industries. Herein, tunable holes and vacancies in nickel hydroxide (h-Ni(OH)2) by the Ostwald ripening process are successfully fabricated, and the as-prepared electrocatalysts are used for the selective ECO of alcohols into acids or aldehydes with excellent electrocatalytic activity and stability, where a selectivity above 92% to benzoic acid with a benzyl alcohol conversion of 99% on 1.0 h-Ni(OH)2 was obtained, while a selectivity of >94% to benzaldehyde with a conversion of >90% could also be achieved once the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical was employed. A paired electrolysis system is employed using 1.0 h-Ni(OH)2 and 1.0 PtO2/h-Ni(OH)2 as electrocatalysts at the anode and cathode, respectively, to simultaneously achieve the selective ECO of benzyl alcohol and H2 production, resulting in a high faradaic efficiency of 192.9%. The excellent ECO activity is mainly due to the abundance of holes and vacancies which facilitate the diffusion rate of the reaction species, adjust the electronic structure and surface properties of h-Ni(OH)2, and change the charge density around benzyl alcohol, thereby enhancing the adsorption energy of the alcohol. This study introduces a new avenue for the understanding and future design of advanced defect-based electrocatalysts for electrosynthesis and energy conversion.
- Chen, Xianlang,Zhong, Xing,Yuan, Bowen,Li, Suiqin,Gu, Yongbing,Zhang, Qiaoqiao,Zhuang, Guilin,Li, Xiaonian,Deng, Shengwei,Wang, Jian-Guo
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p. 578 - 588
(2019/02/14)
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- Method for preparing ketone or carboxylic acid through catalytic oxidation of secondary alcohol or primary alcohol
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The invention relates to a method for preparing ketone or carboxylic acid through catalytic oxidation of alcohol. The method specifically comprises the following steps: adding secondary alcohol or primary alcohol into a certain amount of organic solvent to serve as a raw material, forming an N-hydroxyphthalimide (NHPI)-phthalocyanine catalytic system and taking oxygen as an oxidant, and reacting for 9-36 hours at the reaction temperature of 60-120 DEG C under the condition of normal pressure to obtain the ketone or carboxylic acid with higher yield. Compared with the prior art, the method hasthe advantages of green and environment-friendly oxidant, cheap and easily-prepared catalyst, easiness in separation from the product, mild reaction conditions and the like, and is a green alcohol oxidation method.
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Paragraph 0054-0057
(2019/12/02)
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- Cyclohexyl-Fused, Spirobiindane-Derived, Phosphine-Catalyzed Synthesis of Tricyclic ?3-Lactams and Kinetic Resolution of ?3-Substituted Allenoates
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A C2-symmetric chiral phosphine catalyst, NUSIOC-Phos, which can be easily derived from cyclohexyl-fused spirobiindane, was introduced. A highly enantioselective domino process involving pyrrolidine-2,3-diones and γ-substituted allenoates catalyzed by NUSIOC-Phos has been disclosed. Diastereospecific tricyclic γ-lactams containing five contiguous stereogenic centers were obtained in high yields and with nearly perfect enantioselectivities. A kinetic resolution process of racemic γ-substituted allenoates was developed for the generation of optically enriched chiral allenoates.
- Wu, Mingyue,Han, Zhaobin,Li, Kaizhi,Wu, Ji'En,Ding, Kuiling,Lu, Yixin
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supporting information
p. 16362 - 16373
(2019/10/16)
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- Amorphous SiO2 catalyst for vapor-phase aldol condensation of butanal
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Vapor-phase aldol condensation of butanal to form 2-ethyl-2-hexenal was carried out over several oxide catalysts such as SiO2-Al2O3, Al2O3, ZrO2, and SiO2. Catalysts with moderate and strong acid sites such as Al2O3 and SiO2-Al2O3 were active for the reaction in the initial period, whereas they deactivated rapidly. In contrast, SiO2 with weak acidity showed a low but a stable catalytic activity for the formation of 2-ethyl-2-hexenal. Thermogravimetric analyses of the samples used after the reactions indicate that SiO2 has the smallest amount of carbonaceous species that contributed to its stable activity among the tested catalysts. SiO2 catalysts with different pore sizes and specific surface areas were examined: SiO2 with a mean pore diameter of 10 nm and a surface area of 295 m2 g?1 showed the best catalytic performance and gave a 2-ethyl-2-hexenal selectivity of 90% at a conversion of 48% at 240 °C. In the catalytic test using deuterated SiO2, which was prepared by contacting SiO2 with deuterated water before the reaction, it was confirmed by a mass spectrometer that the deuterium atom of SiOD was transferred to a 2-ethyl-2-hexenal molecule during the reaction. It is indicated that silanol groups on the SiO2 surface played a role as an active site.
- Sun, Daolai,Yamada, Yasuhiro,Sato, Satoshi
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p. 113 - 119
(2018/11/25)
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- TiO2-supported molybdenum carbide: An active catalyst for the aqueous phase hydrogenation of succinic acid
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TiO2-supported Mo carbides “MoC/TiO2” were prepared by impregnation of Mo salt followed by temperature programmed reduction-carburization using 20% v/v C2H6/H2. Catalysts were characterized by XRD, XPS, TEM, STEM, ICP, Raman, BET, and carbon elemental analysis. The catalytic activity was evaluated for aqueous phase hydrogenation of succinic acid at 160–240 °C, and 90–150 bar of H2 in batch reactor. MoC/TiO2 is active for this reaction. The main products after 24 h are γ-butyrolactone, and more remarkably butyric acid. These intermediates are then converted to tetrahydrofuran, butanol, 1,4-butanediol and butane. The reaction conditions (temperature, pressure) do not impact the products distribution. A larger amount of butyric acid is formed when catalysts were synthesized with a higher gas hourly space velocity. The deactivation observed while recycling the catalyst was mainly attributed to a decrease in the amounts of carbidic molybdenum and carbidic carbon, as demonstrated by XPS analysis.
- Abou Hamdan, Marwa,Loridant, Stéphane,Jahjah, Mohamad,Pinel, Catherine,Perret, Noémie
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- Supramolecular photochemistry of encapsulated caged: Ortho -nitrobenzyl triggers
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ortho-Nitrobenzyl (oNB) triggers have been extensively used to release various molecules of interest. However, the toxicity and reactivity of the spent chromophore, o-nitrosobenzaldehyde, remains an unaddressed difficulty. In this study we have applied the well-established supramolecular photochemical concepts to retain the spent trigger o-nitrosobenzaldehyde within the organic capsule after release of water-soluble acids and alcohols. The sequestering power of organic capsules for spent chromophores during photorelease from ortho-nitrobenzyl esters, ethers and alcohols is demonstrated with several examples.
- Kamatham, Nareshbabu,Raj, A. Mohan,Givens, Richard S.,Da Silva, José P.,Ramamurthy
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p. 2411 - 2420
(2019/10/21)
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- Formal Deoxygenative Hydrogenation of Lactams Using PNHP-Pincer Ruthenium Complexes under Nonacidic Conditions
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A formal deoxygenative hydrogenation of amides to amines with RuCl2(NHC)(PNHP) (NHC = 1,3-dimethylimizadol-2-ylidene, PNHP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H2 (3.0-5.0 MPa) to amines at a temperature range of 120-150 °C with 1.0-2.0 mol % of PNHP-Ru catalysts in the presence of Cs2CO3. This process consists of (1) deaminative hydrogenation of secondary amides to generate primary amines and alcohols, (2) dehydrogenative coupling of the transient amines with alcohols to generate imines, and (3) hydrogenation of imines to give the formally deoxygenated secondary amine products.
- Ogata, Osamu,Nara, Hideki,Matsumura, Kazuhiko,Kayaki, Yoshihito
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supporting information
p. 9954 - 9959
(2019/12/24)
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- Functional characterization of salt-tolerant microbial esterase WDEst17 and its use in the generation of optically pure ethyl (R)-3-hydroxybutyrate
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The two enantiomers of ethyl 3-hydroxybutyrate are important intermediates for the synthesis of a great variety of valuable chiral drugs. The preparation of chiral drug intermediates through kinetic resolution reactions catalyzed by esterases/lipases has been demonstrated to be an efficient and environmentally friendly method. We previously functionally characterized microbial esterase PHE21 and used PHE21 as a biocatalyst to generate optically pure ethyl (S)-3-hydroxybutyrate. Herein, we also functionally characterized one novel salt-tolerant microbial esterase WDEst17 from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. Esterase WDEst17 was further developed as an efficient biocatalyst to generate (R)-3-hydroxybutyrate, an important chiral drug intermediate, with the enantiomeric excess being 99% and the conversion rate being 65.05%, respectively, after process optimization. Notably, the enantio-selectivity of esterase WDEst17 was opposite than that of esterase PHE21. The identification of esterases WDEst17 and PHE21 through genome mining of microorganisms provides useful biocatalysts for the preparation of valuable chiral drug intermediates.
- Wang, Yilong,Xu, Yongkai,Zhang, Yun,Sun, Aijun,Hu, Yunfeng
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supporting information
p. 769 - 776
(2018/03/29)
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- Lipase and Laccase Encapsulated on Zeolite Imidazolate Framework: Enzyme Activity and Stability from Voltammetric Measurements
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Abstract: Lipase (Pseudomonas fluorescens) and laccase (Trametates versicolor) were encapsulated on two zeolite imidazolate framework, ZIF-8 and ZIF-zni, materials using a one-pot synthesis-immobilization method in aqueous solution at room temperature. Th
- Naseri, Maryam,Pitzalis, Federica,Carucci, Cristina,Medda, Luca,Fotouhi, Lida,Magner, Edmond,Salis, Andrea
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p. 5425 - 5433
(2018/11/23)
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- Method for preparing low carbon acid from low carbon alcohol
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The present invention provides a method for preparing a low carbon acid from a low carbon alcohol, particularly a method for preparing a low carbon acid in a homogeneous reaction system by catalytically oxidizing a low carbon alcohol, wherein the oxidant of the catalytic oxidation reaction is hydrogen peroxide or t-butyl hydroperoxide, and the catalyst is a water-soluble or alcohol-soluble heteropolyphosphatotungstate or a tungstic acid catalyst. According to the present invention, the preparation method has advantages of simpleness, low production cost, environmental friendliness and high product yield.
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Paragraph 0017; 0018; 0021; 0027; 0028
(2018/11/04)
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- A Sustainable Method for the Synthesis of Acetic Acid Based on Dehydrogenation of an Ethanol–Water Solution Catalyzed by an Iridium Complex Bearing a Functional Bipyridonate Ligand
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An efficient system for the synthesis of acetic acid via dehydrogenation of an ethanol–water solution using a new iridium catalyst bearing a functional bipyridonate ligand with N,N-dimethylamino substituents was developed. Quantitative production of acetic acid from an ethanol–water solution was achieved. In addition, recovery and reuse of the catalyst using a simple procedure was also accomplished. Moreover, this catalytic system can be applied in the dehydrogenative transformation of various primary alcohols to the corresponding carboxylic acids.
- Kuwahara, Masato,Nishioka, Masaaki,Yoshida, Masato,Fujita, Ken-ichi
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p. 3636 - 3640
(2018/06/04)
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- An Efficient Aerobic Oxidation Protocol of Aldehydes to Carboxylic Acids in Water Catalyzed by an Inorganic-Ligand-Supported Copper Catalyst
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A method for the aerobic oxidation of aldehydes to carboxylic acids in water by using an inorganic-ligand-supported copper catalyst was developed. This method was performed with the use of atmospheric oxygen as the sole oxidant under extremely mild aqueous conditions, and furthermore, a wide range of aldehydes with various functional groups were tolerated. The copper catalyst could be recycled and used in successive reactions at least six times without any appreciable degradation in performance. This method is operationally simple and avoids the use of high-costing, toxic, air/moisture-sensitive, and commercially unavailable organic ligands. The generality of this method gives it potential to be used on the industrial scale.
- Yu, Han,Ru, Shi,Zhai, Yongyan,Dai, Guoyong,Han, Sheng,Wei, Yongge
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p. 1253 - 1257
(2018/02/16)
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- Green synthesis of low-carbon chain nitroalkanes via a novel tandem reaction of ketones catalyzed by TS-1
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A green and efficient one-pot method has been developed for the synthesis of low-carbon chain nitroalkanes via a novel TS-1 catalyzed tandem oxidation of ketones with H2O2 and NH3. The tandem reaction including ammoxidation, oximation and oxidation of oximes, afforded up to 88% yield and 98% chemo-selectivity requiring only 90 min, at 70 °C and atmospheric pressure. Moreover, this method was even amenable to 100-fold scale-up without loss of chemical efficiency with 87% yield, represents a significant advance towards industrial production of nitroalkanes. Furthermore, the plausible mechanism of TS-1 catalyzed tandem oxidation of ketones to prepare nitroalkanes was proposed.
- Chu, Qingyan,He, Guangke,Xi, Yang,Wang, Ping,Yu, Haoxuan,Liu, Rui,Zhu, Hongjun
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